Secondary Stats Display: right-aligned values, row spacing, per-stat colors

[labrie75]

What does this PR do?

Readability pass on the Secondary Stats overlay, plus a house-style color picker for it.
At a glance:

Area	Before	After
Value alignment	one left-justified FontString; numbers start wherever the label ends	label / value columns; values right-aligned
Row spacing	lines sit directly on top of each other	SetSpacing(3), scaled with the font
Secondary colors	class color for everything	one hue per stat (gold / green / blue / violet), value colored with its label
Tertiary colors	class color	unchanged (class color)
Color options	one swatch, one-way (no way back to the default)	Default / Class Color / Custom Color swatch trio on the row; Class / Custom pair in the cog

Overlay (EllesmereUIQoL.lua)

• Labels and values split into two columns sharing font/size/spacing; values right-aligned
• SetSpacing(3) between rows, scaled with the font
• Default hues: Crit ffd100 / Haste 2ecc71 / Mastery 55aaff / Vers c77dff,
  value colored with its label; tertiaries stay class-colored

Locale label widths differ a lot (see the two screenshots) -- the value column absorbs all of it.

Options (EUI_QoL_Options.lua)

• Row: Default / Class Color / Custom Color swatch trio, minimap-border style (active one bright, naming tooltips)
• Cog: tertiary Class Color / Custom Color pair (a multiswatch row)
• Custom swatch: first click selects custom, second click opens the picker -- so returning to a default is one click

Compatibility

• Old profiles behave the same: a stored custom color still wins; everything else (position, scale, tertiary toggle, secret-safe values) is untouched
• No new locale keys -- every label and tooltip reuses existing ones

How was it tested?

Tested in game on the 12.1 PTR with a koKR client: default palette with tertiary rows enabled,
overlay rescaling, and the swatch selectors (switching between Default / Class Color / Custom Color on the row and the tertiary pair in the cog, and picking a custom color, which flips its group to custom).

Values stay right-aligned as the numbers change width and the row gap scales with the font.
No load errors.

Screenshots

Same overlay on an English client (left) and a Korean client (right):

Checklist

• New settings default OFF -- the two color-mode keys default to the previous behavior (unset = old default / stored custom color)
• Zero cost while disabled -- the section still early-returns when the overlay is off
• Cheap while enabled -- same update path; one extra FontString, built once
• No writes onto Blizzard-owned frames -- the addon's own overlay frame only
• Tested in-game, works on the 12.1 PTR; no load errors